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Biomedical subjects

C Hannoun

Publications and source records attributed to C Hannoun.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Arbovirus infections and viral haemorrhagic fevers in Uganda: a serological survey in Karamoja district, 1984.

Sera collected in May 1984 from 132 adult residents of Karamoja district, Uganda, were examined by haemagglutination inhibition tests for antibodies against selected arboviruses, namely Chikungunya and Semliki Forest alphaviruses (Togaviridae); dengue type 2, Wesselsbron, West Nile, yellow fever and Zika flaviviruses (Flaviviridae); Bunyamwera, Ilesha and Tahyna bunyaviruses (Bunyaviridae); and Sicilian sandfly fever phlebovirus (Bunyaviridae); and by immunofluorescence tests against certain haemorrhagic fever viruses, Lassa fever arenavirus (Arenaviridae), Ebola-Sudan, Ebola-Zaïre and Marburg filoviruses (Filoviridae), Crimean-Congo haemorrhagic fever nairovirus and Rift Valley fever phlebovirus (Bunyaviridae). Antibodies against Chikungunya virus were the most prevalent (47%), followed by flavivirus antibodies (16%), which were probably due mainly to West Nile virus. No evidence of yellow fever or dengue virus circulation was observed. A few individuals had antibodies against Crimean-Congo haemorrhagic fever, Lassa, Ebola and Marburg viruses, suggesting that these viruses all circulate in the area.

Adult↗
PubMedDate not supplied

[Rimantadine in the prevention and treatment of influenza A].

Although the antiviral properties of rimantadine specifically directed against influenza A viruses have been known for more than 25 years, this compound has not been widely used owing to its narrow specificity. The drug is active and has low toxicity. It should play a major role in the fight against the medical, epidemiological and economic effects of influenza A, but it can only be used under a number of conditions: accurate identification of the circulating virus and early administration of the drug (these two prerequisites being somewhat contradictory), selection of the right targets (contacts of recognized cases, subjects constantly exposed to contagion, etc.) and respect of certain contraindication. On the other hand, the theoretical advantages of this type of prophylaxis are important: it may limit contagion (morbidity) or at least reduce the severity of the cases (mortality); it may also prevent an epidemic from penetrating the population treated and thus reduce the severity and costs of the epidemic. The therapeutic use of rimantadine has not yet been officially recommended, but it already seems very promising. Rimantadine should be used as an adjuvant treatment, side by side with immunization against influenza which it cannot replace.

Adamantane↗
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Natural infection of dogs by influenza C virus.

To date, only one seroepidemiological survey, carried out in Japan, gave a strong indication that dogs may be naturally infected by the influenza C virus, long considered to be exclusively human. In the present work, 134 serum samples were collected during the winter of 1988/89 from dogs aged 6 months to 16 years in northern France. Samples were tested for the presence of antibodies to influenza C virus by both haemagglutination inhibition (HI) and ELISA. Using antibody absorption by staphylococcal protein A, we demonstrated the specificity of the results. In 62% of cases, the results were identical using the two methods. Significant HI activity was found in 32% of the 134 tested sera and titres ranged from 20 to 320. Of the sera tested, 42% were positive by ELISA and titres ranged from 500 to 8,000. The discordant results are discussed. The population tested was divided into five age groups: less than 4 years, 4 to 6 years, 7 to 9 years, 10 to 11 years and greater than 12 years. The distribution of antibodies in the tested canine population, in contrast to that of humans, did not show a significant degree of association with age.

Aging↗
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Comparison of biological and physical properties of human and animal A(H1N1) influenza viruses.

The study of biological properties of influenza virus strains belonging to the same subtype A(H1N1) and closely antigenically related, but isolated from different animal species (man, pig and duck), demonstrated that avian strains were more resistant than those isolated from mammals to high temperature and low pH, as shown by titration of residual infectivity in cell cultures (MDCK) and by sialidase assay. The difference in behaviour could be correlated to biological adaptation of the virus to its host. Avian body temperature is 40 degrees C and influenza virus, in ducks, is enterotropic and therefore capable of passing through the low pH values in the upper digestive tract of the animal. These results do not contradict the hypothesis of a possible filiation between avian and mammalian orthomyxoviruses.

Animals↗
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Bunyaviruses and Bunyaviridae.

A new family is described, the Bunyaviridae, which contains a single genus, Bunyavirus. The main characteristics of the family are as follows: single-stranded RNA, total molecular weight about 7 X 10(6) daltons, probably in three segments. Virions spherical, enveloped particles 90-100 nm in diameter. Envelope contains at least one virus-specified glycopeptide. Develop in the cytoplasm, mature by budding into smooth-surfaced vesicles in the Golgi region or nearby. Internal ribonucleoprotein composed of long strands 2-2.5 nm broad. There are at least 150 members, 87 serologically related bunyaviruses and other probable bunyaviruses.

Arboviruses↗
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[The concept of risk in influenza (author's transl)].

The evaluation of morbidity risk is difficult in influenza because of a lack of accurate quantitative information and of a high variability of the virus. The level of specific herd immunity towards epidemic strains is an important factor of prevision. As far as mortality is concerned, there is a net and regular increase of risk up from the age of 45. In addition to elderly, other high risk categories are known such as patients suffering of a number of organic deficiences or chronical conditions, pregnant women and children. The best evaluation of efficacy of vaccines is the study of incidence reduction in a vaccinated group in comparison to unvaccinated controls. Present vaccines are really efficient to reduce the risk of getting the disease, except in the case of an antigenic shift, which means the activity of a new antigenic component. These advantages are to be weighted to the small risk of vaccine reactions, which are not frequent and usually benign. Several vaccination strategies can be used. In France, it has been decided to recommand vaccine to priority groups: people over 65 and deficient patients. This policy is eqlivalent in many western countries (West Europe, USA); it is not efficient in preventing or delaying epidemics.

Aged↗
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Antibody response to anti-A/New Jersey/76 vaccines.

Experimental inactivated influenza vaccines prepared with strain X 53, derived from A/New Jersey/76 virus were injected to several groups of subjects. Different compositions of vaccine were used and the subjects were selected from different age groups. Antibody responses were measured 15 days after vaccination; it was then possible to evaluate the conversion rates, the percentages of subjects showing a protective level of antibodies and the average level of antibodies. The results show that a very small dose of antigen, probably acting as a booster, gives very good results in the older age group. On the other hand, young adults (below 23) react to a much lower degree to the vaccine. The results are discussed in relation to the age distribution of preexisting antibodies in the experimental groups and in the general population in France.

Adult↗
PubMedDate not supplied

Effects of vaccination on an influenza epidemic in a geriatric hospital.

During winter 75/76 (from February 1 to March 31) we got the opportunity to follow the incidence of an influenza epidemic that occurred in the geriatric hospital of Ivry. Its population was, on the average, 83 years old. 958 persons were involved in this study: 523 out of them had been vaccinated with Pasteur bivalent Mutagrip A + B vaccine. The epidemic had a double origin: it was due to a virus A/Victoria and to a virus B/Hong Kong. A significant difference was noted between the vaccinated group and the nonvaccinated one. Serological (CF and HI) and virological investigations (virus isolation) were performed on 110 subjects. The clinical course followed by the disease was mild for the vaccinated and severe for the nonvaccinated. Mortality rate was 0.19% in the former against 3.90% in the latter. It has been thus possible to observe an "immunological fence" since it appears that when 79% of a given unit has been vaccinated, influenza incidence has been as much as three times reduced.

Aged↗
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Isolation from birds of influenza viruses with human neuraminidase.

Attempts at virus isolation from cloacal swabs resulted in the recovery of 10 strains of hemagglutinating viruses from a total of 349 ducks, mainly shelducks (Tadorna tadorna) captured in the north of France. Four of these isolates were identified as influenza strains corresponding to the following antigenic composition: Hav6-N2, Hav6-Nav4 and Hav1-N2 (2 strains). Shelduck is known to be a partially migratory species, wintering in western Europe, some of them migrating northward to Scandinavia during the summer. The captures were made between November 1976 and February 1977: one of the birds was caught four times and was found to be negative for virus in November, positive in December (isolation of a strain Hav6-Nav4), negative again in January and February. Blood taken in February did not show the presence of HI antibodies to the homologous virus.

Animals↗
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[Tick-borne encephalitis in Europe (author's transl)].

Tick-borne encephalitis is the major european arbovirosis. It is observed in Soviet Union, Central and Western Europe and Scandinavian countries. In France, natural foci have been detected in Alsace (more specialy in Illkirch forest, near Strasbourg). In the United Kingdom exists a sheep encephalomyelitis (loupingill) caused by an arbovirus not much different from the tick-born encephalitis virus. The tick-born encephalitis virus is a flavivirus transmitted by tick bites. Tick is also a virus reservoir; it remains infected all along its life, through its metamorphosises and transmits the virus to its progeny. Vector-ticks belong to various species of a same genus; Ixodes persulcatus in Far-Eastern Soviet Union, Ixodes ricinus in other european foci. Small rodents (field-mouse, vole) are mainly the prime vertebrate hosts. Man is more often infected by the tick bite, more rarely by ingestion of new milk from infected domestic animals. Prognosis of the disease is under geographical variations: severe in Far-Eastern Russia and much milder in Central Europe. Natural foci are detected by serological surveys in patients recovering from neurologic diseases, human populations and in domestic animals. Natural foci beeing localized, isolation and identification of the virus from ticks and local rodents are tried. Extension and creation of new natural foci are caused by big mammalians and by migratory birds which carry over virus and vector ticks. Prophylaxis for people going to or living in registered natural foci, consists of avoiding ticks bites by wearing tight clothes and using repellents. Immunization by a recent vaccine produced in Austria from cultures on chicken embryo has given promising results.

Animals↗
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[Role of mutations and recombinations in the epidemiology of influenza].

Influenza virus demonstrates several levels of antigenic variations, drifts and shifts, which help it to escape to herd immunity pressures. Recent examples show the importance of such variations in the succession and continuity of epidemiological manifestations. During the last few years, simultaneous circulation of several subtypes of influenza A was observed while in the past, one subtype was replacing the other. Thus in 1981, for the only subtype H3N2, A/Texas, A/Bangkok and A/intermediate Texas-Bangkok viruses were isolated in France at the same time in several foci. Furthermore, double infection with different subtypes in the same individual have been documented in man as well as in animals (birds). Related strains have also been isolated simultaneously in the same individual and cloning by plaque analysis makes it possible to evaluate easily this possibility in wild strains. The unexpected frequency of double infections or of variations of virus in feral animals or humans increases the possibility of genetic reassortments and participates for an important part to global variability of the virus.

France↗